Hi - my 4.2 First Edition Sport is misfiring on idle - the spark plugs have just been changed and the diagnostics read out is displaying P0302 cylinder 2 misfire
P0303 cylinder 3 misfire
P0304 cylinder 4 misfire
P0308 cylinder 8 misfire

i have replaced all 8 spark plugs and coil packs of the cylinders that have registered a fault,

misfire is only really noticeable on idle, once a steady engine speed is held it runs much better

engine management light is not on at the moment

Was this a problem before you changed the plugs

Yes - the engine management light was on too....but now off...

Would an engine ECU reflash /update help?

Not sure an ecu reflash will help, that will clear any fault codes stored, but i'd check the maf sensor first.

Ok thanks - will do

Generally, such misfires can also be classified as "random misfires".
And the possible causes would be:

* ECM to ignition coil primary circuit faults
* Ignition coil failure
* Spark plug failure/fouled /incorrect gap
* Fuel delivery pressure (low/high)
* Fuel injector circuit fault(s)
* Fuel injectors restricted/leaking
* Fuel injectors continuously open
* Fuel contamination
* Cylinder compression low
* Worn camshaft/broken valve springs
* Valve clearance adjustment

Use an approved diagnostic tool to do some coil tests, check the spark plug condition and gap, check the fuel pressure, check for fuel injector problems. Malaysia Boleh!
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Thanks - the spark plugs and coil packs have been changed a week ago by a senior BMW technician - he identified one of the old spark plugs was not in properly. The new ones are all in as they should be now.

Never trust a BMW technician... Next he will be telling you to trade in your sport for an X5 Are you sure he hasn't sabotaged your sport just for this reason

Lol - I hope not - we both work at the same diagnostics company....

Hi guys

Did you manage to cure this problem as I have the same problem with my 2006 4.2 sport. Mine is misfiring on cylinders 3 and 5,the misfire clears after 1000 rpm. any advice would be very grateful

The misfire is still there on all eight cylinders - more noticeable on start up - but then subsides as the engine warms up.

Overall it drives nice and smooth but it's still very annoying that the misfire exists - after all the diagnosing and money spent.

Mine does exactly the same - misfire on startup and idle - and engine management light comes on and stays in until reset. Dealer found a bit of oil in one of the spark plugs, which they dried and apparently its better now. I told them to keep the car until they 100% sure that the issue has been resolved.

Let me know when you get it back and if the dealer did any more work to rectify...

Cheers

DC

will do